[2] Early scholarly work focused on interannual variation in the form of mast seeding in tree species such as pines and oaks.
[3] This suggested that trees produced large amounts of seeds in response to favorable resource availability and weather conditions.
Subsequent research has shown that while weather and resource availability may act as proximate mechanisms for interannually synchronized flowering, the ultimate driver is adaptive evolution for increased mating opportunities.
Such broad patterns are prone to disturbance by anthropogenic change such as global warming and the introduction of invasive species.
Little has been done to examine synchrony across plant functional groups[4] (i.e. trees and herbaceous annuals and perennials), though differences in pollination syndromes complicate such analyses.
More work is needed to understand how global shifts in flowering plant communities will reshape ecosystems.
Synchronously-flowering species in a community may evolve other divergent traits to avoid competition and prevent the transfer of heterospecific pollen.
More work is needed to determine whether species’ flowering synchrony can evolve due to the composition of the community they inhabit.
Wind-pollinated species exhibit may flower in conjunction with trade winds to take advantage of more effective pollination conditions.
[31] Determining the degree to which within-year flowering synchrony is a consequence of the constraints of abiotic resource availability versus an evolved trait with fitness benefits is a field of research requiring further work.
In ecosystems which experience distinct growing seasons and winters, flowering time is limited to periods with adequate temperature and light.
This results in community synchrony simply due to the fact that plants may be physiologically incapable of flowering in the dead of winter.
[4] In the high latitudes of the tropics, where plant communities are not constrained by unfavorable weather, flowering times could diverge due to selective or pressures or simply because of genetic drift.
[33] In addition to these patterns, plants at lower latitudes more frequently exhibit interannual flowering synchrony.
Irregularly disturbed environments can result in the evolution of asynchronous reproduction, which is more robust to catastrophic damage to a population.
[2] The unrestricted growing season of the tropics may allow for speciation due to shifts in flowering periods,[33] especially where microclimate variation among metapopulations exist.
Asynchronous reproduction between congeners can be maintained by differential responses to abiotic cues, preventing hybridization.
[37] Flowering synchrony could shift and evolve in concert with novel mutualist pollinator or antagonistic predator, resulting in speciation, though this has not been empirically demonstrated.
[38] The loss of mutualist frugivores (particularly vertebrates) due to habitat reduction can also decrease selective pressure for asynchronous reproduction.
Community synchrony has the potential to increase as asynchronously-flowering species are filtered out by local extinction due to lack of available mates.
[39] Habitat fragmentation increases edge effects in populations, potentially creating greater microclimate variation and decreasing synchrony due to uneven abiotic cues.
A study found that plant communities assembled with a high diversity of differently-colored flowers, potentially to avoid competition for pollinators attracted to particular colors in floral displays.
[44] By reshaping the phenology of coevolved animal species, climate change has the potential to disrupt selection for reproductive synchrony.